1. Field of the Invention
The present invention relates to a speech communication apparatus, and more particularly to a speech communication apparatus in which a speech communication microphone is mounted on a speech communicator in such a manner as to be fixed in the vicinity of the mouth of said speech communicator.
2. Description of Background Art
A communication system (an intercom) is known in which in order to establish speech communication between a rider and a driver of a riding type vehicle such as a motorcycle and a passenger of said riding type vehicle a speaker or a rider or driver of another vehicle, a speech communication microphone and an electric contact between them are mounted in a helmet for the driver, the passenger and the driver of another vehicle, respectively, and a communication unit mounted on the vehicle side is connected to the helmet for the driver, the passenger and the driver of another vehicle, respectively.
In the conventional communication system described above, since the speech communication microphone is normally fixed in the vicinity of the mouth of the driver when the helmet is worn by the driver, the speech communication microphone cannot be moved away from the vicinity of the mouth even when the driver feels like sneezing or coughing. This causes a problem that noise generated when the driver sneezes or coughs is allowed to be entirely detected by the speech communication microphone for transmission to the passenger or the driver of another vehicle who is in communication with the driver, thereby making his or her speech communication partner feel uncomfortable.
Although there exists no prior art developed to solve the technical problem described above, as a common technology for attenuating an excessive input which offends the ear JP-A-5-183363 discloses a technology in which a signal exceeding allowable positive or negative maximum values is converted into a code of a noise level at which noise cannot be substantially picked up by converting an input signal into a digital signal for data processing.
In the above prior art, the input signal is converted into the digital signal, the digital signal resulting from the conversion is data processed to determine whether or not the input signal is excessive, and if it is determined to be excessive the excessive input signal must be converted into a string of codes. Thus, there has been caused a problem that the construction of the prior art speech communication system becomes complicated.